ELAC2, a RNaseZ activity in humans, endonucleolytically cleaves pre-tRNAs near the 3' end, generating a 3' hydroxyl group to which the nucleotides CCA will be polymerized (Takaku et al. 2004, Yan et al. 2006, Elbarbary et al. 2008). ELAC2 is located in both the nucleus and mitochondria (Brzezniak et al. 2011). ELAC1, a homologue of ELAC2, is located in the cytosol (Rossmanith 2011) and cleaves 3' ends of tRNAs in vitro (Takaku et al. 2003).